According to a study, if frequent supply of vitamin B12 isn't absorbed by your body, the deficiency can turn into megaloblastic anaemia leading to gastrointestinal abnormalities. Megaloblastic anaemia is a condition whereby the bone marrow produces usually large, structurally abnormal, immature red blood cells that aren't able to transport oxygen effectively around the body.
According to the National Organisation of Rare Disorders (NORD), gastrointestinal abnormalities include diarrhoea and nausea. A lack of healthy red blood cells can also make some people lose their appetite. When symptoms of anaemia are more apparent, you may suffer from fatigue, shortness of breath, lightheadedness and dizziness.
Common effects on a person experiencing megaloblastic anaemia include pale skin colouring. You could also encounter a fast or irregular heartbeat when you're deficient in vitamin B12. An adequate supply of the vitamin is required for the body and mind to function normally. Vitamin B12 is found in meat, fish, and eggs. Those who follow a vegetarian or vegan diet are usually at high risk of these complications. They are also at the risk of the nutrient not being effectively absorbed by the body – called malabsorption.